TiOx / IrOx anode catalyst and preparation method and application thereof
Through the preparation of TiOx/IrOx hollow core-shell structure anode catalyst, the problems of high catalyst stability and cost in the prior art are solved, and the efficient and low-cost hydrogen production performance of PEM electrolytic water is achieved, which is suitable for commercial PEM electrolytic water technology .
Patent Information
- Application Number
- CN202411242752.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-05
- Publication Date
- 2024-12-10
AI Technical Summary
In the existing PEM electrolytic hydrogen production technology, metal oxide catalysts are difficult to exist stably under acidic and strong oxidation conditions, resulting in high catalyst costs, limiting the large-scale commercial application of the technology, and insufficient catalyst activity, affecting efficiency.
TiOx/IrOx hollow core-shell structure anode catalyst is used, and the titanium and iridium sources are reduced and annealed in sequence by the template method to form an orderly hollow core-shell structure, reducing the amount of precious metal iridium and improving the activity and stability of the catalyst.
A catalyst with high quality activity and low precious metal content has excellent catalytic properties, can obtain high current density at lower iridium loading and voltage, and improves the economic and stability of PEM electrolyzed hydrogen production.
Smart Images
Figure CN119101952A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of catalysts, and particularly relates to a TiO x / IrO x Anode catalyst and preparation method and application thereof. Background Art
[0002] As an efficient and clean energy carrier, hydrogen energy has the advantages of zero emission and high energy density. Proton exchange membrane (PEM) water electrolysis to produce hydrogen has the characteristics of high current density, fast dynamic response speed, good compatibility with renewable energy, compact equipment structure and convenient deployment in limited space. With the rapid development of renewable energy and the reduction of electricity costs, PEM water electrolysis to produce hydrogen technology will be more widely used in the future.
[0003] The oxygen evolution half-reaction (OER) at the anode of PEM water electrolysis involves a multi-electron reaction, and its slow kinetics and high reaction energy barrier greatly limit the overall efficiency of the water electrolysis process. Since most metal oxides are difficult to stably exist under acidic and strongly oxidizing conditions, the catalysts currently used in commercial PEM water electrolysis for hydrogen production mainly rely on IrO2. However, the high cost and scarce reserves of IrO2 limit the large-scale commercial application of PEM water electrolysis. Therefore, it is urgent to develop a high-quality, active, low-iridium catalyst to reduce the amount of precious metals used, thereby reducing the cost of PEM water electrolysis technology and improving its economic benefits. Summary of the invention
[0004] The technical problem to be solved by the present invention is to provide a TiO x / IrO x The anode catalyst and its preparation method and application overcome the defects of the prior art. The invention improves the quality activity of the catalyst and achieves the purpose of reducing the content of the noble metal iridium in the catalyst.
[0005] The present invention provides a catalyst, which is a hollow core-shell structure, wherein IrO x For the shell, TiO x is the nuclear layer; <x<2。
[0006] Furthermore, the catalyst is an anode catalyst; and the hollow core-shell structure is a nanomaterial.
[0007] Preferably, the catalyst is prepared from a raw material containing a template, a titanium source and an iridium source, by sequentially reducing the titanium source and the iridium source on the surface of the template and then removing the template.
[0008] The present invention provides a method for preparing a catalyst, comprising:
[0009] A titanium source and ammonia water are added to the template solution for reaction, and then an iridium source is added for reaction, calcined and annealed, and the template is removed to obtain a catalyst.
[0010] Preferably, the template includes one or more of an inorganic template and an organic template; wherein the inorganic template includes at least one of NaCl and SiO2; the organic template includes one or more of a polymer template and an organic ammonium base template; the solvent of the template solution is ethanol, and the mass ratio of ethanol to template is 120 to 180:1.
[0011] Preferably, the titanium source includes one or more of tetrabutyl titanate, titanium isopropoxide, titanium trichloride, and titanium tetrachloride; the iridium source includes one or more of iridium trichloride, iridium tetrachloride, potassium hexachloroiridate, chloroiridic acid, iridium acetylacetonate, and tetrairidium dodecacarbonyl.
[0012] Preferably, the molar ratio of the titanium source to the iridium source is 1 to 100:1.
[0013] Preferably, the titanium source and ammonia water are added to the template solution, and the reaction is carried out at 80° C. to 100° C. for 1 h to 4 h, wherein the adding method is dropwise addition; wherein the mass ratio of the titanium source to the ammonia water is 1:1 to 3.
[0014] Preferably, the iridium source is added and reacted at 80° C. to 100° C. for 1 h to 4 h; a reducing agent is added simultaneously with the addition of the iridium source; wherein the reducing agent is ethylene glycol, and the molar ratio of ethylene glycol to the iridium source is 2 to 6:1.
[0015] Preferably, the calcination annealing is annealing at 350° C. to 550° C. for 1 h to 6 h.
[0016] The present invention provides a membrane electrode, characterized in that the membrane electrode contains the catalyst according to claim 1.
[0017] The present invention provides a method for preparing a membrane electrode, comprising: coating the catalyst slurry on a PEM to obtain a membrane electrode, wherein the coating method includes ultrasonic spraying, scraping, rod coating, etc.; wherein the catalyst slurry is prepared by dispersing the catalyst in a mixed solution of water and ethanol.
[0018] The invention provides an application of the membrane electrode in proton exchange membrane water electrolysis.
[0019] The present invention provides a method for preparing a high-performance ordered hollow core-shell titanium-iridium catalyst, which maximizes the stabilizing effect of titanium and the catalytic properties of iridium, so that the membrane electrode with low iridium loading prepared by the method exhibits excellent catalytic activity. Based on the invented catalyst, the present invention develops one or several membrane electrode preparation processes, which are suitable for users of various coating equipment, and the membrane electrodes prepared by different processes all have excellent PEM water electrolysis hydrogen production performance.
[0020] The present invention provides a high-performance ordered TiO x @IrO x The preparation scheme of the composite catalyst selects templates of various specifications, uses various titanium compounds as titanium sources, and uses various iridium compounds as iridium sources. The titanium source and the iridium source are sequentially coated on the surface of the template using a liquid phase reduction strategy, and an ordered core-shell structure composite catalyst is obtained after annealing and template removal. According to the different titanium-iridium loading ratios, the feed ratio of titanium-iridium can be adjusted in the range of 1 to 100:1. The obtained composite catalyst exhibits unique performance advantages in electrocatalytic applications, and the amount of precious metals in the catalyst is significantly reduced, which helps to improve its economy in practical applications.
[0021] The present invention relates to a high-performance ordered TiO x @IrO x The membrane electrode process of the composite catalyst is developed. The catalyst is prepared into slurry, and the catalyst slurry is evenly coated on the PEM by ultrasonic spraying, slit coating and other means to prepare a membrane electrode. The membrane electrode, gas transfer layer, flow field plate, current collector, etc. are assembled into an electrolyzer to test the performance and stability of water electrolysis. The iridium loading at the membrane electrode anode is only 0.5mg / cm 2 It still has good performance and stability.
[0022] Beneficial Effects
[0023] (1) TiO obtained by the present invention x @IrO x Composite catalysts have unique structural advantages and abundant active sites.
[0024] (2) Compared with commercial iridium dioxide, the catalyst obtained by the present invention has high mass activity and low noble metal content, while also having good stability.
[0025] (3) TiO obtained by the present invention x @IrO x The composite catalyst was prepared into a membrane electrode. At a lower iridium loading (0.5 mg / cm 2 ) and a relatively low voltage (2V) can achieve a high current density (4A / cm 2 ).
[0026] (4) TiO developed by the present invention x @IrO x The composite catalyst slurry is not only suitable for users of ultrasonic spraying equipment, but also for customers of slit coating, blade coating, rod coating and other equipment. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1The ordered TiO prepared in Example 1 x @IrO x Synthesis route of composite anode catalyst;
[0028] Figure 2 The ordered TiO prepared in Example 1 x @IrO x Transmission electron microscopy (TEM) image of composite anode catalyst;
[0029] Figure 3 The ordered TiO prepared in Example 1 x @IrO x Polarization curve of composite anode catalyst in acidic electrolyte, the voltage has been converted to standard hydrogen electrode potential; the above data was obtained by testing with Jiangsu Donghua DH7002A electrochemical workstation;
[0030] Figure 4 The ordered TiO prepared in Example 1 x @IrO x Polarization curve of composite anode catalyst in PEM electrolyzer; the test temperature is 80℃;
[0031] Figure 5 The ordered TiO prepared in Example 1 x @IrO x Composite anode catalyst; the test temperature was 60°C and the current density of the stability test was set to 2A / cm 2 . DETAILED DESCRIPTION
[0032] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.
[0033] Example 1
[0034] Preparation of TiO x @IrO xAnode catalyst: 100 mg of silica templating agent with a size of 200 nm was dispersed in 20 ml of absolute ethanol. 0.56 g of tetrabutyl titanate and 0.9 g of ammonia water were slowly dropped into it, and it was placed in an 80 °C water bath and stirred for 1 h. 0.08 g of iridium(III) chloride and 0.04 g of ethylene glycol were added to it, stirred and dispersed thoroughly. After reacting for 2 h, the product was washed repeatedly 3 times, and after drying, it was transferred to a porcelain boat. The porcelain boat was placed in a muffle furnace and annealed at 350 °C for 1 h. After cooling with the furnace, the product was stirred in an alkaline solution for 3 h to remove the templating agent, and then the product was washed repeatedly with ultrapure water to obtain the target catalyst.
[0035] Some structural and performance studies were carried out on the materials prepared by the above method.
[0036] As Figure 1 shown is the synthesis route diagram of the obtained TiO x @IrO x (0 < x < 2) composite anode catalyst.
[0037] As Figure 2 shown is the TEM image of the obtained TiO x @IrO x anode catalyst, indicating that the templating agent in the catalyst has been completely removed, and IrO x is uniformly loaded on the substrate TiO x to form an ordered hollow core-shell structured composite catalyst.
[0038] The prepared TiO x @IrO x anode catalyst was studied for its electrocatalytic oxygen evolution performance in a three-electrode system with a 0.5 M H2SO4 electrolyte, where TiO x @IrO x was the anode (working area: 0.071 cm 2 ), a platinum wire was the counter electrode, and a saturated calomel electrode was the reference electrode. It should be noted here that the main battery of the electrochemical workstation was the external power supply for electrocatalytic oxygen evolution; the potential obtained with the saturated calomel electrode as the reference electrode was converted to the reversible hydrogen electrode potential in the property diagram.
[0039] As Figure 3 shown is the polarization curve of the obtained TiO x @IrO x anode catalyst under the test conditions of a three-electrode system, indicating that the catalyst has good oxygen evolution reaction activity, where the overpotential required when the current density reaches 10 mA / cm 2 is 279 mV.
[0040] The prepared TiO x @IrO xThe anode catalyst was prepared into a membrane electrode by ultrasonic spraying for PEMWE activity evaluation. It is pointed out that the cathode end catalyst is Pt / C, the gas diffusion layer is a porous transport layer with a straight through pore structure, the test temperature is 80°C, and the active area is 5cm 2 The iridium loading is 0.5 mg / cm 2 .
[0041] like Figure 4 TiO x @IrO x Polarization curve of anode catalyst in PEM electrolyzer. Test results show that TiO x @IrO x The anode catalyst has high activity in the PEM electrolyzer. At a voltage of 1.8V, the current density reaches 2.4A / cm 2 At 2V, the current density reaches 4.0A / cm 2 .
[0042] like Figure 5 TiO x @IrO x Stability curve of anode catalyst in PEM electrolyzer. Test results show that TiO x @IrO x The anode catalyst has high stability in the PEM electrolyzer at 60°C and 2A / cm 2 At a current density of , the electrolyzer operated stably for 2000 h.
[0043] Example 2
[0044] As in Example 1, the template is replaced with silicon oxide or other inorganic and polymer templates of sizes such as 20nm, 50nm, 100nm, 150nm, 250nm, 300nm, etc., and other conditions remain unchanged, and highly ordered core structure TiO x @IrO x Composite anode catalyst, and the overpotential deviation does not exceed 20mV.
[0045] Example 3
[0046] As in Example 1, the iridium source is changed to one of iridium trichloride, iridium tetrachloride, potassium hexachloroiridate, chloroiridic acid, iridium acetylacetonate, tetrairidium dodecacarbonyl, etc., and other conditions remain unchanged, and highly ordered core structure TiO x @IrO x Composite anode catalyst, and the overpotential deviation does not exceed 20mV.
[0047] Example 4
[0048] As in Example 1, the tetrabutyl titanate was changed to one of titanium isopropoxide, titanium trichloride, titanium tetrachloride, etc., and other conditions remained unchanged, and a highly ordered core structure TiO x @IrO x Composite anode catalyst, and the overpotential deviation does not exceed 20mV.
[0049] Example 5
[0050] As in Example 1, the reaction temperature was changed from 80°C to 90°C, the reaction time was increased from 1h to 4h, and other conditions remained unchanged, and highly ordered core-structured TiO x @IrO x Composite anode catalyst, and the overpotential deviation does not exceed 10mV.
[0051] Example 6
[0052] As in Example 1, the calcination temperature was adjusted from 350°C to 550°C, the calcination time was increased from 1h to 6h, and other conditions remained unchanged, and highly ordered core structure TiO x @IrO x Composite anode catalyst, and the overpotential deviation does not exceed 15mV.
[0053] Example 7
[0054] As in Example 1, the membrane electrode preparation process was changed from ultrasonic spraying to scraping, rod coating and other processes. The prepared membrane electrode still had excellent performance (the electric density reached 4A / cm2 when <2V). 2 ) and stability (at 1A / cm 2 Stable operation for more than 1,000 hours).
Claims
1. A catalyst, characterized in that The catalyst is a hollow core-shell structure, wherein IrO x For the shell, TiO x is the nuclear layer; <x<2。 2. The catalyst according to claim 1, characterized in that The catalyst is obtained from raw materials containing a template, a titanium source and an iridium source by sequentially reducing the titanium source and the iridium source on the surface of the template and then removing the template.
3. A method for preparing a catalyst, comprising: A titanium source and ammonia water are added to the template solution for reaction, and then an iridium source is added for reaction, calcined and annealed, and the template is removed to obtain a catalyst.
4. The preparation method according to claim 3, characterized in that: The template includes one or more of an inorganic template and an organic template; wherein the inorganic template includes at least one of NaCl and SiO2; the organic template includes one or more of a polymer template and an organic ammonium base template; the solvent of the template solution is ethanol, and the mass ratio of ethanol to the template is 120 to 180:
1.
5. The preparation method according to claim 3, characterized in that: The titanium source includes one or more of tetrabutyl titanate, titanium isopropoxide, titanium trichloride, and titanium tetrachloride; the iridium source includes one or more of iridium trichloride, iridium tetrachloride, potassium hexachloroiridate, chloroiridic acid, iridium acetylacetonate, and tetrairidium dodecacarbonyl; The molar ratio of the titanium source to the iridium source is 1 to 100:
1.
6. The preparation method according to claim 3, characterized in that: The titanium source and ammonia water are added to the template solution, and the reaction is carried out at 80° C. to 100° C. for 1 h to 4 h, wherein the adding method is dropwise addition.
7. The preparation method according to claim 3, characterized in that: The iridium source is added and reacted at 80° C. to 100° C. for 1 h to 4 h; a reducing agent is added simultaneously with the addition of the iridium source; wherein the reducing agent is ethylene glycol, and the molar ratio of ethylene glycol to the iridium source is 2 to 6:1; The calcination annealing is annealing at 350° C. to 550° C. for 1 h to 6 h.
8. A membrane electrode, characterized in that: The membrane electrode contains the catalyst according to claim 1.
9. A method for preparing a membrane electrode, comprising: The catalyst slurry according to claim 1 is coated on a proton exchange membrane (PEM) to obtain a membrane electrode.
10. Use of the membrane electrode according to claim 8 in proton exchange membrane water electrolysis.